Merc 50 Starter Problem

[Jonesky]

A friend has an 86 Merc 50. The starter would spin but the bendix did not elevate and engage the flywheel. Lubed bendix and checked for sticking. Checked/cleaned connections at battery, solenoid and starter. No change. Then checked voltage at the battery, solenoid and starter - all 12+. Also tried different fully charged battery and "jumped" it direct to starter bypassing the solenoid. Still no change. Determined it was probably internal to the starter and replaced it with a new one. New starter will not elevate either so I am now scratching my head. Anyone have an idea for me?

 

[JB]

Re: Merc 50 Starter Problem

Howdy,

Welcome to iboats.

The electric circuit that drives the Starter has many potential sites for trouble that has nothing to do with the starter motor itself, Jonesky.

Go to the Engine FAQs Forum and do the starter circuit troubleshooting in "Outboard won't start".

Let us know what you find, and good luck.

 

[Silvertip]

Re: Merc 50 Starter Problem

When doing voltage measurements, were those taken with the key in the START position (load). A discharged battery can still read close to 12.6V with no load on it. Are you sure the second battery was good. Have you jumped directly to the starter with the other battery? Did you use a single jumper cable or did you use two (one from BAT NEG to engine block and the POS cable direct to starter). If that process failed to spin up the bendix you still have one of two issues: 1) weak battery or 2) bad starter or bendix. That process eliminates everything except the starter and battery. Check to make sure the starter is turning in the right direction (battery cables reversed?????). An if that was the case you can now start looking for a new rectifier.

 

[Jonesky]

Re: Merc 50 Starter Problem - Solved!

Re: Merc 50 Starter Problem - Solved!

Thanks to both of you. I figured out the problem. My friend had taken the old starter off to check it out and reinstalled it prior to me looking at it. After reading your advice, I reran the diagnostics from the faq and still couldn't figure out what was wrong. I then ran some resistance tests and found the problem. The meter indicated a dead short between where he had incorrectly installed the "hot wire" on the upper starter terminal and the engine ground. My friend had reversed the hot wire from the solenoid and the ground wire on the starter.poles. This meant the starter was running in reverse and could not spin up the bendix. I reinstalled the wires correctly and she worked like a champ.

I really do appreciate the help.